1. Field of the Invention
The present invention relates to an air passage device, particularly a filter fan or outlet filter.
2. Description of the Related Art
In the case of components arranged in a housing, which generate corresponding waste heat, it is necessary to carry off the waste heat from the housing and control a temperature in the housing by blowing in or drawing off ambient air into the interior of the housing to a greater or lesser extent by means of the fan. Computer housings are a known example of this. Usually, such housings are provided with a filter fan which either runs continuously or is switched on and off by a control arrangement, depending on a temperature in the housing. The filter fan is arranged in a recess of a wall of the housing and is fixed for example by means of screw connections. At the same time, corresponding air outlet slits are provided for the outlet of air at another location in the housing. However, the installation of such filter fans is frequently laborious, because when screw connections are used, there is scarcely any play available in order to be able to also subsequently visually align the filter fan.
The filter mats which are used in these filter fans are arranged between the outer fan grid and the base housing. The fan grid is detachably connected to the base housing by means of clamping- or detent connections or screw connections. If a used filter mat is to be exchanged for a new filter mat, the entire fan grid must be removed from the base housing, with the connection means in most cases having to be loosened by means of tools.
A filter fan housing with an air inlet on the base side and an air outlet which is at right-angles to the air inlet, with the air outlet opening being connected with the interior of a switch box, is known from DE 100 51 643 A1. In the interior of the housing, a filter mat is arranged which assumes an oblique position, so that the air current is guided from the air inlet to the air outlet through the filter mat. The interior of the filter mat housing is accessible via a closable maintenance opening, in order to be able to exchange a filter mat.
DE 40 13 645 A1 discloses an air filter for an electronics housing, which is constructed such that an exchanging of the filter mats is to be possible without interrupting the operation of the apparatus. To do this, the air filter has a filter mat by means of which dust and impurities are able to be removed from an air current which is drawn in from the outside, and a support in which the filter mat is mounted and which comprises a holding frame and a handle for manipulating the support. Furthermore, holding arrangements are provided for the engaging hold of the support in/on the housing with a tight closure with respect to ventilation openings of the housing and guide arrangements, which are mounted on the housing such that the support is movable through an insertion opening in the housing along the guide arrangements to the holding arrangements and out again and is able to be engaged into the holding arrangements.
On the one hand, the filter fan mounts a specially constructed housing, so that the air current can be directed at an angle from the inlet to the outlet through the interior of the housing, which has a separate, closable maintenance opening, in order to be able to grasp hold of the filter mat through the maintenance opening in order to exchange it, whilst on the other hand the air filter housing is provided with a maintenance opening in order to be able to exchange via the latter the filter mat which is constructed in the manner of a cassette.